Lightning arrester



Feb. 12 1924. 1,483,539

c. T. ALLCUTT LIGHTNING ARRESTER Filed a 7, 1919 WITNESSES: ENVENTOR /W fifiafer m mrz ATTORNEY Patented Feb. 12, 1924.

UNITED STATES 1,483,539 PATENT OFFICE.

CHESTER T. ALLCUTT, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8: MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

LIGHTNING ARRESTER.

Application filed Kay 7,

To all whom it may concern:

Be it known that I, CHESTER T. ALLCUTT, a citizen of the United States, and a resident of Pittsburgh, in the county of Alle gheny and State of Pennsylvania, have invented a new and useful Improvement in Lightning Arresters, of which the following is a specification.

My invention relates to lightning arresters and it has particular relation to arresters wherein two electrodes composed of con ducting material are spaced a art by means of a discharge block. The ob eot of my invention is to provide an arrester of the character indicated wherein any discharge of current through the block caused by a voltage slightly above normal will be allowed to pass to ground without, in any way, afl'ecting the arrester and wherein any excessive discharge of current or any continuous discharge of current of any value will automatically increase the resistance thereof to a point which will render a continuous flow of current through the established path impossible, thereby causing the discharge to seek a new path, provided the voltage is still above normal.

Heretofore, it has been suggested to place a block of carbon or similar refractory conducting material between two plate elec; trodes and to place a filler of lead peroxid between the carbon and the electrodes. The electrodes are each provided with an insulating film on the side adjacent the lead peroxid which prevents continuous passage of a current therethrough when a di erence of otential exists between the two electro es.

By my invention, I provide an arrester in which the carbon block is replaced by a discharge block formed of a porous non-combustible, non-conducting material which eliminates the necessity of the insulating film and causes the breakdown characteristics thereof to vary in a manner similar to air-gap breakdown characteristics.

In the accompanyin drawing, I'show an arrester provided wit a conducting plate or electrode 1 connected to a supply circuit 2 and a similar conducting plate or electrode 3 spaced therefrom and connected to ground at 4. The plates 1 and 3 are spaced apart by means of a discharge block 5 composed of some porous inorganic insulating material, such as asbestos, spun glass or very 1919. Serial No. 295,812.

porous porcelain. Intermediate the conducting plates and the discharge block 5 are disposed layers 6 of lead peroxid or some similar material which is normally of relatively low resistance and is converted by heat into a material of relatively high resistance.

In an arrester of this type, any small discharge of current of short duration causezl by a similar voltage surge will pass through the lead peroxid, leap the multiple air-gap composed of the spaces in the discharge block material and through the second layer of lead peroxid, and the remaining electrode to ground, without causing any change in the arrester, the cooling effect of the discharge block being suflicient to prevent any heating thereof at the sides adjacent the layers of lead peroxid. However, if a current continues to pass through the arrester, the discharge block will be heated thereby and will, in turn, heat the lead peroxid at the ends of the particular path established and thus convert it into a lower oxid of relatively great resistance.

If, for any reason, the discharge block is defective so that there is a tendency for a continuous current to flow during periods of normal potential on the supply circuit, the action of the lead peroxid will seal the defective portion thereof, thus restoring the arrester to its originally intended dischargevoltage breakdown.

While I have shown but one form of my invention and have described in detail only one application of the same, it will be um derstood by those skilled in the art that it is not so limited but is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or are specifically set forth in the appended claims.

I claim as my invention:

1. An electrical-discharge device comprising a plurality of spaced conducting members, means disposed intermediate said members embodying a layer of porous noncombustible material and a layer of a metal compound which becomes converted by heat into a compound of high resistance.

2. An electrical-discharge device comprising a plurality of spaced conducting members, means disposed intermediate said members embodying a layer of comminuted non-combustible material and a layer of conductive oXid which becomes converted by heat into a difierent oxid of higher electrical resistance.

3. An electrical-discharge device comprising a plurality of spaced conducting members, means disposed intermediate said members embodyin a layer of porous non-combustible material and a layer of a metal compound of low heat conductivity andlow electrical resistance which becomes converted by heat. into a compound of different chemical composition and high electrical resistance.

An electrical-discharge device comprising plurality of spaced conducting members, means disposed intermediate said members embodying a layer of porous noncombustible material and a layer of lead peroxid.

5. A lightning arrester comprising two spaced conducting plates .each provided with a layer of lead peroxid and a body of porous non-combustible material disposed therebetween.

6. A lightning arrester comprising two spaced conducting plates, one of which is connected to a source of electromotive force and the other of which is connected to ground, a body of porous inorganic insulating material disposed between said plates, and a layer of lead peroxid disposed between said body of insulating material and each of said plates.

7. An electric-discharge device comprising a plurality of spaced electrodes, means disposed intermediate said electrodes embodying a body of material the dielectric stre th of which equals that of air and a layer of conductive oxid which becomes converted by heat into a different oxid of higher electrical resistance.

8. An electrical-discharge device comprising a plurality of spaced electrodes, means disposed intermediate said electrodes embodying-a body of material the dielectric strength of which equals that of air and a layer of a metal compound which becomes converted by heat into a compound of high resistance.

9. An electrical-discharge device comprising a plurality of spaced electrodes, means disposed intermediate said electrodes embodying a body of material, the dielectric strength of which equals that of air and a layer of material, the resistivity of which increases with an increase with current passing therethrough.

10. An electrical-discharge device comprising a plurality of spaced electrodes, means disposed intermediate said electrodes embodying a body of material, the dielectric strength of which equals that of air and a layer of lead peroxid.

11. A lightning arrester comprising two spaced conducting plates, one of which is connected to a source of electromotive force and the other of which is connected to ground a body of non-combustible insulating material disposed intermediate said plates and provided with a plurality of minute air passages extending between said lates, and a layer of lead peroxid disposed between said body of insulating material and each of said plates.

In testimony whereof, I have hereunto subscribed my name this Qlth day of April,

CHESTER T. ALLCUTT. 

